Voltage regulating system



Feb. 14, 1961 e. A. PHELAN 2,972,098

VOLTAGE REGULATING SYSTEM Filed July 25, 1956 IN V EN TOR. GEORGE ,4.PHELA IV ,qITbRN y United States Patent Ofifice VOLTAGE REGULATINGSYSTEM George A. Phelan, East Orange, NJ., assignor to The BendixCorporation, a corporation of Delaware Filed July 25, 1956, Ser. No.600,141

4 Claims. (Cl. 32224) The present invention relates to generator systemsand more particularly to means for maintaining close control of theregulated voltage of a variable frequency A.C. generator.

In the past, various arrangements for maintaining a constant outputvoltage for an AC. generator have been utilized. Quite a few of thesehave incorporated moving parts and required considerable time forwarm-up in order to have a stabilized output.

The present invention provides a regulating system utilizing a magneticamplifier which has no moving parts and requires no warm-up period forsatisfactory operation. Further, it provides close regulation over awide range of generator speeds.

It is an object of the invention to provide an improved voltageregulating system.

Another object of the invention is to provide an improved regulatingsystem for a generator wherein no moving parts are used.

Another object of the invention is to provide an improved magneticamplifier regulating system.

Another object of the invention is to provide a novel regulating systemthat requires no warm-up period.

The above and other objects and features of the invention will appearmore fully hereinafter from a consideration of the following descriptiontaken in connection with the accompanying drawing, wherein oneembodiment is illustrated by way of example.

In the drawing:

The single figure is a schematic diagram of a regulating systemembodying the invention.

Referring now to the drawing, an A.C. generator is indicated generallyby the numeral 1 and includes a rotor winding 2 and a three phase statorwinding 3. While a three phase winding has been illustrated, it isunderstood that it is not limited thereto. Output conductors 3A, 3B, 3Cand 3N are connected to the stator windings 3. An exciter 4 is providedto energize the winding 2. The exciter 4 and winding 2 may be drivenfrom any suitable source (not illustrated). The exciter 4 has a shuntfield 5, bucking field 6 and ballast resistor 7, and armature winding 8.The output of the winding 8 is connected by conductors 9 and 10 throughconventional slip rings to the winding 2. v

The energization of the winding is controlled by a magnetic amplifier 11of the series reactor type. The amplifier 11 has an alternating currentwinding 12, a main control winding 13, trimmer windings 14 and 15, andfeedback winding 16. The amplifier 11 may be of the toroidal type.

A transformer 17 has-a primary winding 18 connected by conductors 19 and20 across output conductors 3A and 3N. The transformer 17 has secondarywindings 21 and 22. One side of the winding 21 is connected by conductorto contacts 25 of a relay 24 through switch arm 26 and conductor 27 toone side of the winding 12 of the reactor 11. The other side of thewinding 12 is connected by conductor 28 to one input terminal of arectifier 29. The other input terminal of the rectifier winding 21 ofthe transformer 17.

One output terminal of the rectifier 29 is connected by a conductor 31to the side of the winding 5 which is connected to one side of thewinding 6 and ballast resistor 7. The other output terminal of therectifier 29 is connected by conductors 32 and 33 in series with awinding 34 of a transformer 35 to the other side of the winding 5. Oneend of feedback winding 16 is connected by conductor 36 to the sameoutput terminal of rectifier 29 as the conductor 31. The other end ofthe winding 16 is connected by conductor 37, temperature compensatingnetwork 38, conductor 39, Winding 40 of a transformer 41, conductor 42,winding 43 of the transformer 35, conductor 44 and conductor 32 to theother output terminal of the rectifier 29. A stabilizing network 45 maybe connected across the output of the rectifier 29.

A rectifier 46 is connected by conductors 47 and 48 across the winding22 of the transformer 17 One output terminal of the rectifier 46 isconnected by conductor 49 to one side of the bucking winding 6. Theother output terminal of the rectifier is connected by conductor 50 tothe other side of the winding 6. A resistor 51 may be provided in theconductor 50 to limit the current in the winding 6.

The main control winding 13 of the magnetic amplifier 11 is energized bya bridge circuit 52 which has voltage regulator tubes 53A and resistor54A in one leg and tubes 53B and resistor 548 in the other leg. Thebridge 52 has one output terminal connected by con ductor 55 to one sideof the winding 13 and the other output terminal connected by conductor56 to the other side of the winding 13. A resistor 57 may be inserted inthe conductor 56. The input terminals of the bridge 52 are connected byconductor 58, resistor 59 and conductor 60 across the output of arectifier 61. The rectifier 61 is energized from the output of thegenerator 1 by being connected by conductors 62 and 63 across outputlines 3A and 3B. A capacitor 64 may be connected across the output ofthe bridge 52.

Trimmer windings 14 and 15 of the amplifier 11 are connected across theoutput of an electronic sensing circuit 65 by conductors 66, 67 and 68.The circuit 65 is described and claimed in Emerson US. Patent No.

2,611,121 and a detailed description thereof will be omitted here forthe sake of brevity. The circuit 65 is energized from the output of themachine 1 by a transformer 69 connected by conductors 70 and 71 acrossthe output lines 3A and 3B.

The transformer 41 has a winding 72 connected by conductors 73, 74 andresistor 75 across the armature winding 8 of the exciter 4. A controlwinding 76 of a carbon pile regulator 77 is connected by conductors 78,79 and resistor 7 across the winding 8. i 'A resistor 80 may be insertedin the conductor 79. The carbon pile regulator is illustrateddiagrammatically as having an armature 81 pivoted at 82 and biased by aspring 83 in a direction to compress a stack of carbon disk 84 inopposition to the winding 76. One side of the stack 84 is connected tothe conductor 78 and the other side is connected by conductor 85 to acontact 86 on relay 87 and also to a contact 88 on relay 89.

The relay 87 has a switch member 90 connected to the conductor 33 andwhen in the deenergized position is biased into engagement with thecontact 86. Also on the relay 87 are contact 91 and associated switchmember 92. A control winding 93 is connected across the output of arectifier 94. One input terminal of the rectifier 94 is connected by aconductor 95 to the output line 3B. The other input terminal of therectifier 94 is connected by conductor 96, resistor 97, conductor 98,resistor 99 and conductor 100 to the output line 3C. A shunt PatentedFeb. 14, 1961 is provided for the resistor 97 by conductor 1G1 connectedto the contact 91, switch arm 92 and conductor 102. The function andoperation of the relay 87 is described and claimed in copendingapplication Serial No. 600,132 filed July 25, 1956.

The relay 89 in addition to the contact 88 has a switch arm 103 and acontiol winding 104. The switch arm 103' in the u'nen'ergizd position isbiased to engage the contact 87. The winding 104 is connected byconductors T and 106 across the output of a rectifier 167. A re sistor108 may be inserted in the conductor 1%. The input of the rectifier 107is connected by conductors 169 and 110 across the winding 21 of thetransformer 17. Also connected across the output of rectifier 107 bycondoctors 111 and 112 is a control winding 113 for the relay 24. Aresistor 114 may be inserted in the conductor 112. The function andoperation of the relay are described and claimed in copendingapplication Serial No. 600,131 filed July 25, 1956.

In operation, the output voltage of the generator 1 is controlled byregulating the output of the exciter 4. Output voltage is sensed by thebridge circuit 52, the output of which energizes the control winding T13of the magnetic amplifier 111 in a direction depending upon the.

direction of deviation of the output voltage from a predetermined value.In addition to the main control winding, a pair of trimmer windings areprovided. They are energized from an electronic sensing circuit whichsenses R.M.S. values and provides a highly sensitive control for theamplifier 11.

A feedback winding 16 is connected in a combination shunt feedback andstabilizing circuit. The stabilizing circuit has two transformers, theprimary winding of one is connected in series with the exciter shuntfield and the primary of the other across the rotating field. Thesecondary windings are connected in series with the feedback windingacross the output rectifier of the magnetic amplifier.

In order to limit the ampere turn range required on the shunt fieldwinding of the exciter, a bucking field Winding is provided. The buckingfield winding is-errergized from a rectifier connected to the A.C.output of the generator.

The relay 2,4 is provided to prevent the magnetic amplifier from goingto saturation upon the removal of a short circuit on the stator of thegenerator or from some other transient condition. A control windingresponsive to generator voltage is adjusted to actuate the relay 24 toan open circuit position upon the output voltage reaching apredetermined value to open the A.C. input to the magnetic amplifier.The A.C. voltage collapses. The starting relay 89 is then in position togive full field to the exciter and the output voltage will build up in anormal manner and the system is back to normal operating conditions. a

The relay 87 provides means for limiting short circuit currents to asafe value. Upon a short circuit occurring, the voltage will collapseand the relay 87 will go to the closed position, as shown in thedrawing. This will insert a carbon pile element in the shunt fieldcircuit. The

control winding'o'f the carbon pile is connected to sense" the currentin the rotating field. A ballast resistoilis connected in series withthe control winding to provide temperature compensation. Thus,independent of generator speed, the rotating field current is heldconstant and thereby keeps the short circuit current constant and withinsafe'lirnits.

7 Although only one embodiment of the the invention has 1 beenillustrated and described, various changes in the 1. A voltageregulating system for an alternating cure rent generator having a directcurrent exciter, said exciter having a shunt field winding, a buckingfield winding and an armature winding, comprising a saturable devicehaving an alternating current winding, a main control winding, trimmerwindings and a feedback winding, circuit means for energizing saidalternating current winding from the output of said generator, voltagesensing means responsive to the output voltage for energizing said maincontrol winding, electronic means for energizing said trimmer windingsin accordance with the R.M.S. value of said output voltage, said lasttwo windings coacting to provide a cumulative control for saidalternating current winding, means for energizing said shunt fieldwinding from the output of said alternating current winding, means forenergizing said bucking winding in accordance with said generator outputvoltage in a direction to oppose said shunt field winding, and astabilizing circuit connected in series with said feedback windingacross the output of said alternating current winding.

2. A static voltage regulator for an alternating current generator,comprising a magnetic amplifier energized from said generator output, afirst sensing circuit for providing a control current for said magneticamplifier in accordance with the average value of said generator output,a second sensing circuit for providing a control current for saidmagnetic amplifier in accordance with the R.M.S. value of said generatoroutput, said control currents coacting to provide a cumulative control,circuit means connecting the output of said magnetic amplifier to excitesaid generator, and antihunting means connected across the output ofsaid generator to. effect said excitation in a direction to opposetransient changes.

3. The combination as set forth in claim 2 and incl-uding meansenergized from said generator output to oppose said excitation.

4. A voltage regulating system for an alternating current generatorhaving a direct current exciter which has a shunt field winding and anarmature winding, comprising a series saturablc reactor, said reactorhaving an A.C. winding, a main control winding, trimmer winding, and afeedback winding, circuit means including arelay for connecting saidA.C. winding for energization from the output of said alternatingcurrent generator, a sensing circuit responsive to the average value ofsaid generator output connected to energize said main control windingaccording to said average value, a second sensing circuit responsive tothe R.M.S. value of said generator output connected to energize saidtrimmer windings in a direction determined by the direction of'deviationof said output from a predetermined value, said control winding and saidtrimmer windings coacting to control the output of said A.C. winding,means including a rectifier for con meeting the output of said A.C.winding toenergize said.

shunt field winding, and an antihunting circuit inchrding said feedbackwinding connected inseries .with a pair of stabilizing transformersacross the output of said rectifier,

one of said transformers having a winding connected in series with saidshunt fieid, and the other of said transformers having a windingconnected across said armature winding.

References Cited in the fileof this patent UNITED STATES PATENTS2,161,179 Logan June 6, 2,394,Q49- Fisher Feb. 5, 1946 2,571,827 BradleyOct. 16, i 2,665,402 Clark z ]ar1.. 5, 1954 2,666,885 Bradley et a1.Jan, 19,1954 7 2,715,205 Ringland Aug; '9, 1955 2,738,457 t GilchristMar. 13, 1956 2,773,232 Herbst et 51. 1350.4, 1956

